driver.java

Java程序设计(美) David D. Riley著 机械工业出版社 书籍配套 代码

import java.awt.*;
/**	Money Test Program using Labels  (Figure 6.33)
 *	Author: David Riley
 */
public class Driver extends ThreeButtons {
	private	Label dollarLabel, quarterLabel;
	private	Label dimeLabel, nickelLabel;
	private MoneyUSA money;
	private ThreeButtonFrame  theWin;

	/**	post:	A window is displays monetary denominations. */
	public Driver()   {
		theWin = new ThreeButtonFrame("Money Counter");
		theWin.setLayout(null);
		dollarLabel = newlyAddedLabel(10);
		quarterLabel = newlyAddedLabel(50);
		dimeLabel = newlyAddedLabel(90);
		nickelLabel = newlyAddedLabel(130);
		money = new MoneyUSA(0, 0, 0, 0, 0);
		updateDisplay();
	}

	/** post:	result is displayed upon theWin誷 content pane
	 *			and  result.getX()==100  and  result.getY()==y
	 *			and  result.getWidth()==100  and  result.getHeight()==30 
	 */
	public Label newlyAddedLabel(int y)   {
		Label result;
		result = new Label();
		result.setBounds(100, y, 100, 30);
		theWin.add(result, 0);
		return result;
	}

	/** pre:	money is instantiated
	 *	post:	money.dollars == money.dollars@pre + 1  
	 */
	public void leftAction()   {
		money.dollars++;
		updateDisplay();
	}
	
	/**	pre:	money is instantiated
	 *	post:	money.quarters == money.quarters@pre + 1
	 *			and  money.nickels == money.nickels@pre + 3  
	 */
	public void midAction()   {
		money.quarters++;
		money.nickels = money.nickels + 3;
		updateDisplay();
	}
	
	/**	pre:	money is instantiated
	 *	post:	money.valueInCents == money.valueInCents@pre
	 *			and money consolidated into largest possible denominations  
	 */
	public void rightAction()   {
		money.consolidate();
		updateDisplay();
	}

	/** pre:	money is instantiated
	 *	post:	the output labels are updated to reflect the
	 *			value of dollars, quarters, dimes, and nickels of
	 *			the money variable  
	 */
	private void updateDisplay()   {
		dollarLabel.setText( "Dollars: " + money.dollars );
		dollarLabel.repaint();
		quarterLabel.setText( "Quarters: " + money.quarters );
		quarterLabel.repaint();
		dimeLabel.setText( "Dimes: " + money.dimes );
		dimeLabel.repaint();
		nickelLabel.setText( "Nickels: " + money.nickels );
		nickelLabel.repaint();
	}
}